1450 PTO blows fuse

[jbrewer]

10 amps of 12v is 120 watts. a 120 watt soldering iron will get very very hot...like 500F hot. 10A should be more than plenty.

If your fuse is in the same part of the circuit as the schematic indicates, then the ONLY load on that branch of the circuit is the PTO.

Some questions for you.

Does the fuse blow when you're actuating the pto, or just driving the tractor?

For a fuse to blow at 45 min , one of two things is probably happening.

1) There's an intermittent short or heavy load that just happened to occur at 45 min.

2) You were pulling right at 10A for an extended time.

Fuses are strange beasts. They're crude and not well characterized. If you look at the specs of a fuse, you'll generally see a fuzzy graph that indicates load versus time. A fuse will go a surprisingly long time at rated load before it clears.

Some more data to work with would be good. Increasing the current rating of the fuse or putting a slow blow in is not a fix.

So what were you doing when the fuse blew?

If the PTO was not actuated and it blew the first scenario is the most likely.

John

[krhoover]

Did you change the guage of the wiring. On mine there is a spade connector that the fuse wire connects to the electric clutch with. On mine that spade connection was oil covered and loaded with dirt. I would look there to make sure you have a good clean connection. After the fuse blows, is the wire hot to the touch. Can you see any discoloration anywhere on the wire/connections that would indicate heat. If so I would start by checking those areas for good connections.

[ol'George]

Check to see if the lead to the PTO coil is frayed/ occasionally rubbing on a ground/frame etc.
If you have checked everything and seem to find no apparent problems, look to see if the connections on/in the fuse holder are clean and tight,
as that can be a problem.
Also on those Electric clutches the insulation cracks/degrades and sometimes the coil can loosen and rub on the rotating disc.
To check that, you will have to partially disassemble PTO.

[jbrewer]

Just another hint. Dirty connections will NOT cause high current flow which is what blows fuses

They will cause lower current flow, which is why it affects starting and charging. They're just another series resistance.

Not trying to take a shot at anyone, just want to optimize your diagnose time. :-)

John

[ol'George]

You are correct, but as I stated in the earlier post, a loose connection IN the fuse holder will cause the fuse to become hot and the solder will melt and the fuse will become inoperative.
I have seen it many times going back 50+ years.

[jbrewer]

You're right, its possible. I doubt it could sink 120 watts + but it's certainly simple to check and fix! :-)

John

[rmidgett]

I found this year old thread while searching for answers to a similar problem with my 1250.
It appears in my case the windings of the field coil have shorted. It's not a hard short to ground, but the winding to ground only shows 2 ohms resistance, and that's too low. It should be four ohms or so for the 3 amp current draw at 12VDC.
Reading about these parts from suppliers supports the notion that over time the winding insulation can break down due to heat & vibration, short out & blow the fuse.
It appears in a short time of researching, a new field coil is only available in a kit, part number 759-3664, and that new kit is ~$500. I only gave $500 for the machine four years ago. Used units (PTO kits) are available on eBay.
I might take a stab at re-winding the field coil..it's just magnet wire potted in epoxy, both of which I've worked with before.

[R Bedell]

Or finding a good used PTO. Perhaps the Sponsors listed above can help you out.

[rmidgett]

Oh, and in the process of troubleshooting the field coil in the clutch, I found what I believe is my primary oil leak....the front seal practically fell off the PTO shaft. I'm glad that seal is still available, and not priced at $500.